Multiple-band detector using frequency selective slots

Abstract

An optical detector pixel element. The novel pixel element includes a metallic substrate having a plurality of resonant apertures, each aperture adapted to resonantly transmit electromagnetic energy in a distinct frequency band, and a plurality of detectors adapted to detect the energy transmitted by the apertures. Each aperture is adapted to collect energy incident on an area larger than the aperture and focus the energy into a smaller, localized region in which one or more of the detectors is placed. The plural apertures are positioned such that they collect energy incident on a substantially common area, but are of different sizes such that they are resonant to different frequencies. Energy in different frequency bands are therefore funneled through different apertures. In an illustrative embodiment, several identical pixel elements are joined together to form an array.

1. An optical detector pixel comprising:
 a metallic substrate having a plurality of resonant apertures, each aperture adapted to resonantly transmit electromagnetic energy in a different frequency band, wherein each aperture has a different size such that each aperture is resonant at a different frequency, and 
 first means for detecting said electromagnetic energy transmitted by said apertures; 
 wherein a surface of the metallic substrate is free of any protruding resonance structure between each of the plurality of apertures. 
 
     
     
       2. The detector pixel of  claim 1 , wherein said first means includes a plurality of detectors. 
     
     
       3. The detector pixel of  claim 2 , wherein at least one detector of the plurality of detectors is positioned beneath each aperture. 
     
     
       4. The detector pixel of  claim 2 , wherein each detector of the plurality of detectors is adapted to absorb electromagnetic energy transmitted by a respective aperture and convert said electromagnetic energy to an electrical signal. 
     
     
       5. The detector pixel of  claim 1 , wherein each aperture of the plurality of resonant apertures is adapted to collect energy incident on an area larger than said each aperture and focus said energy onto a smaller, localized region. 
     
     
       6. The detector pixel of  claim 1 , wherein one or more detectors are placed in a region of focused energy. 
     
     
       7. The detector pixel of  claim 1 , wherein two differently-sized apertures are positioned such that they collect energy incident on a substantially common area. 
     
     
       8. The detector pixel of  claim 1 , wherein said apertures are slots. 
     
     
       9. The detector pixel of  claim 1 , wherein said apertures are bowtie slots. 
     
     
       10. The detector pixel of  claim 1 , wherein said apertures are crosses. 
     
     
       11. The detector pixel of  claim 1 , wherein said apertures are bowtie crosses. 
     
     
       12. The detector pixel of  claim 1 , wherein said electromagnetic energy includes infrared energy. 
     
     
       13. The detector pixel of  claim 1 , wherein said plurality of resonant apertures comprise rectangular slots. 
     
     
       14. The detector pixel of  claim 1 , wherein the different size and a shape of said plurality of resonant apertures are configured to transmit non-polarized electromagnetic energy. 
     
     
       15. An optical detector pixel comprising:
 a metallic substrate having a plurality of resonant apertures of different sizes, each aperture adapted to resonantly transmit light in a different frequency band, and 
 a plurality of detectors wherein at least one detector is positioned beneath each aperture and each detector is adapted to absorb light transmitted by a respective aperture and convert said light to an electrical signal; 
 wherein a surface of the metallic substrate is free of any protruding resonance structure between each of the plurality of apertures. 
 
     
     
       16. An imaging array comprising:
 a plurality of pixels arranged in an array, each pixel including:
 a metallic substrate having a plurality of resonant apertures of different sizes, each aperture adapted to resonantly transmit light in a different frequency band, and 
 a plurality of detectors wherein at least one detector is positioned beneath each aperture and each detector is adapted to absorb light transmitted by a respective aperture and convert said light to an electrical signal; and 
 
 a circuit adapted to receive said electrical signals from said pixels and to generate one or more output images; 
 wherein a surface of the metallic substrate is free of any protruding resonance structure between each of the plurality of resonant apertures. 
 
     
     
       17. A method for simultaneously imaging multiple frequency bands, the method comprising:
 resonantly transmitting incident electromagnetic energy in each frequency band through a different resonant aperture formed in a metallic substrate, wherein each aperture has a different size such that each aperture transmits energy in a different frequency band, and 
 detecting said electromagnetic energy transmitted by said apertures; 
 wherein a surface of the metallic substrate is free of any protruding resonance structure between each of the different resonant apertures.